1. Field of the Invention
The present invention relates to a wired Multiple-Input Multiple-Output (MIMO) link tester; and, more particularly, to a wired link tester, which can check the performance of an MIMO system indoors prior to an outdoor experiment by simulating wireless-channel environments of the MIMO system using a wired link.
This work was supported by the IT R&D program for MIC/IITA [2005-S-404-12, “Research & Development of Radio Transmission Technology for 3G evolution”]
2. Description of Related Art
For development of the communication system, the system is checked by performing an indoor wired test prior to an outdoor wireless test.
Thus, in case of the next-generation communication system supporting high-speed multimedia communication using wide bandwidth and multiple antennas, a scheme for the indoor wired test must be considered that can perform the above operation on a Multiple-Input Multiple-Output (MIMO) system.
In case of the conventional single-antenna system, a transmitting antenna port and a receiving antenna port are connected in a wired fashion, thereby testing the corresponding system under the wireless-channel environment that is most ideal in terms of a modem. In this case, only the operation or not of the system can be detected.
However, in case of the MIMO system, feasibility of the above scheme depends on the formation of transmitting antennas and receiving antennas.
Even when the above wired test scheme can be used, if the number of transmitting antennas is identical to the number of receiving antennas, only the operation or not of the system is detected as in the single-antenna system test. This is however a test under the very-unreasonable condition where a signal transmitted from one transmitting antenna is received only at one receiving antenna.
Also, in case of the conventional single-antenna system, the system can be tested in a wired fashion using a channel simulator that is capable of simulating a general wireless channel.
The channel simulator down-converts a signal received from a transmitting system, simulates the influence of a wireless channel by baseband digital signal processing, and up-converts the resulting signal prior to transmission to a receiving system. The system test using the channel simulator can be a system test under every condition. However, the channel simulator for the system test requires a complex structure and high costs.
Particularly, in case of the MIMO system, the channel simulator for the system test requires more complex structure and higher costs.